This invention is concerned with transfer materials and is specifically concerned with transfer materials which can be used to carry toner images for transfer onto a substrate.
More specifically, the invention relates to materials for use in or with the transfer of full colour and monochrome toner images produced by a xerographic photocopier or a dry toner printer, such as a laser printer, onto a substrate, including paper, card, cardboard, leathers, glass, ceramics, wood, metal, metallised materials, plastics materials, and film form materials and closely woven and closely knitted materials whether or not the surfaces of those materials are plain or have existing artwork thereon, or have been coated with any typical proprietary coating.
Attempts to transfer and so print images have been made previously but until now there has not been a successful attempt to provide a single xe2x80x98universalxe2x80x99 material which can be used both in xerographic photocopiers, laser printers and the like and also permit transfer of full colour images from one surface to another without the use of intermediate means such as adhesive materials and without loss of definition or colour tones or image quality.
Previously, it has been normal practice to use paper and other materials for carrying images which are copied from a photocopier or dry-ink or toner printer, but these images have, until recently, been fixed on the paper or other material as permanent images, the term xe2x80x9cpermanentxe2x80x9d meaning that the image so formed cannot be removed from the carrier without damaging it. In addition, it is also known to transfer images onto self-supporting films for use as overhead projection slides.
In some applications, it has been possible to transfer monochrome images from such paper or the like onto another surface by using special transfer materials but not to the extent that 100% of the image can be transferred, or more importantly that 100% of a full colour image can be transferred.
In the specification of UK patent application no. 9325904.2, there is disclosed a method and material for printing monochrome and full colour images onto a surface, the method comprising the steps of
(a) copying the image onto a carrier to provide a toner image on the carrier,
(b) placing the carrier against film form polyethylene ester material with the toner image between the carrier and the material,
(c) passing the carrier and the material through a heating station whereat, under pressure, the carrier and the material, with the toner image therebetween, are subjected to a temperature in the range of 140-160 degrees Celsius,
(d) thereafter removing the carrier from the material, with the toner image wholly transferred to the material,
(e) placing the material against a surface of a substrate onto which the toner image is to be ultimately transferred with the toner image there between, and
(f) passing the material and the substrate through a heating station whereat, under pressure, the material and the substrate, with the toner image therebetween, are subjected to a temperature in the range of 140-160 degrees Celsius to transfer the toner image from the material to said substrate,
the polyethylene ester material having thermal shrinkage characteristics of less than 1.0%.
The polyethylene ester material is exceptionally useful for printing images onto virtually any surface from an original image formed on paper in a copier or laser printer. However, the polyethylene ester material can not be used in the copier or printer itself and this requires that two separate sets of materials are required for image transfer, namely the one for carrying the initial image and the other for actually transferring the initial image to some other substrate.
With state of the art copiers and laser printers, it is possible to produce mirror images in the copiers themselves and for those mirrored images to be printed. Having that facility, it is then desirable to carry that image directly from the copier or printer onto a medium that will permit transfer of the image directly from the medium onto a substrate that is intended to carry the image permanently, e.g. the surface of a packaging blank.
UK patent specification no. 1215599 discloses a method of reproducing images on objects unsuitable for passage through an electrostatic copying machine, comprising: passing a sheet of material through a xerographic copying machine so that charged particles are distributed over the sheet of material in a pattern corresponding to the image to be reproduced; heating the sheet to cause the particles to adhere to the sheet; and subsequently placing the image-bearing surface of the sheet in contact with a further surface on which the image is required to be reproduced and applying heat and pressure to the said contacting surfaces until the particles transfer from the said sheet to the said further surface and fuse to the latter whereby on separation of the surfaces the fused pattern of particles is exposed on the said further surface. The method is said to be useful in forming images on surfaces of metal, glass, tiles, wood and fabric, and for forming transparencies such as overhead projection (OHP) foils.